In the past week, we’ve seen fervent objections to the news that University of Chicago professor Luigi Zingales has invited former Donald Trump adviser Steve Bannon to take part in a debate at the university over globalization and immigration. Many students and faculty are calling for the invitation to be withdrawn and for Bannon to be banned from campus, since he “traffics in hate speech and white supremacist ideologies."

This is the familiar “hate speech isn’t free speech” argument being used to de-platform or censor campus speakers, usually on the right. But the argument is feeble.

For one thing, it violates the spirit of our First Amendment, which the courts have interpreted to mean that there should be no restrictions on public speech unless it incites clear and present danger. The argument also violates the University of Chicago’s liberal speech code, which states that the proper response to ideas deemed offensive is “robust counterspeech that challenges the merits of those ideas and exposes them for what they are.” Properly, the university has refused to ban Bannon.

The Constitution and the university protect nearly all forms of speech because the free exchange of ideas — the bulwark of education, democracy and the quest for justice — requires that speech be allowed, even when it strongly counters our own beliefs, nearly everyone’s beliefs or, indeed, advocates censorship itself.

Why? Because one person’s hate speech is another person’s free speech. Not so long ago we saw left-wing speakers banned for what was considered “hate speech” — speech in favor of Israel, against abortion or promoting evolution. Banned speakers have included Michael Moore, Eleanor Holmes Norton, Tony Kushner, Richard Dawkins, Julian Bond and even Archbishop Desmond Tutu. This shows that one generation’s “hate speech” can be another generation’s norms.

Further, who gets to decide what “hate speech” is? Whom would you trust to censor speakers? And how would you feel if your own views were censored? That’s why the founders wisely chose to make nobody a censor. Censorship may make you feel vindicated, but it doesn’t eliminate offensive ideas; it only drives them underground. The best disinfectant, and surest path to the truth, is open airing of all views.

President Barack Obama, no friend of Bannon, said this two years ago in his commencement speech at Howard University: “As my grandmother used to tell me, every time a fool speaks, they are just advertising their own ignorance. Let them talk. Let them talk. If you don’t, you just make them a victim, and then they can avoid accountability. … Listen. Engage. If the other side has a point, learn from them. If they’re wrong, rebut them.”

How can you know if your own views are worth holding unless you’ve tested them against the best arguments of your opponents?

I’m no fan of Bannon, either. I consider his views nativist, divisive and repugnant. But there’s still something to be gained by hearing his words, especially in a debate. By all means, let us demonstrate peacefully, write letters and deliver our own counterspeech. But under no circumstances should we try to silence our opponents. That accomplishes nothing. The words “I favor free speech” should never be followed by “but.”

Jerry Coyne is professor emeritus in the department of ecology and evolution at the University of Chicago.